NCERT Class 6 Science Chapter 3 ‘Separation of Substances’: Notes and Solutions (Free PDF)

NCERT Class 6 Science Chapter 3 helps you learn about the need for the separation of substances, the principle of separation, and techniques of separation. In addition, the chapter also sheds light on types of substances and mixtures and methods used to separate unwanted components from the substances. To help you understand all these concepts, we have explained all important terms in detail. Also, to help you prepare for your weekly tests and mid-term examinations, we have solved all questions present in CBSE Class 6 Science Chapter 3 Exercises. 

Explore all the Chapters of Class 6 Science:-

Chapter 1	Chapter 2	Chapter 4	Chapter 5	Chapter 6
Chapter 7	Chapter 8	Chapter 9	Chapter 10	Chapter 11

Also Read: Interesting Science Experiments for Class 6

Summary of NCERT Class 6 Science Chapter 3

CBSE Class 6 Science Chapter 3 will help you to learn about different concepts of separation of substances. In this summary, we have tried to include all possible methods of separation and also explained the necessity for the segregation of substances. 

Separation of Substances Class 6 Notes

Let us now explore the notes of Class 6 Science Chapter 3 and study all the related topics!

Why is the Separation of Substances Necessary?

Separation of substances is necessary because of the following reasons:

• To discard unnecessary components
• To segregate different but necessary components
• To separate harmful or impurities elements 

What is the Principle of Separation?

The components of a mixture retain their original characteristics, such as volatility, melting and boiling points, volatility, density, and particle size. The components of a mixture are divided using the differences in any one of these qualities.

What are Different Methods of Separation?

To separate components from a substance, one can opt for the following separation methods:

• Handpicking
• Threshing
• Winnowing
• Sieving
• Sedimentation, Decantation, and Filtration
• Evaporation
• Condensation

Handpicking

Handpicking is a process of separation used to remove large-sized contaminants from wheat, rice, or pulses, such as particles of dirt, stone, and husk.

Threshing

Beaten stalks are subjected to threshing in order to extract the grains from the harvested crop. Farmers can perform it manually or with threshing equipment.

Winnowing

Winnowing is a method of separation that uses wind or air blowing to separate heavier and lighter components of a mixture. This is typically done to remove the husk from grains.

Sieving

In this method of separation, a filter or a sieve is used to separate the mixture during the sieving process. Larger particles, which are typically contaminants, can’t pass through the filter and end up on the sieve where they gather. The smaller particles can be gathered below as they pass through the sieve.

Sedimentation, Filtration, and Decantation

Sedimentation: It is the process by which the heavier component of a mixture settles when water is added to it. This technique is employed to separate grains from soil and dust.

Filtration: To separate the solid particles from their fluid components through filtration, the mixture is passed through a filter. For instance, we can observe that when muddy water is sent through a fine filter, the muck is filtered out and the water continues to flow.

Decantation: Following sedimentation, a procedure called decantation removes both the water and the contaminants.

Also Read: NCERT Class 6 Science Chapter 1 Notes: Components of Food

Evaporation

Evaporation is the process of turning water into vapour. Everywhere there is water, evaporation is a constant process. A method for separating a mixture, often a mixture of a solvent and a soluble material, is evaporation. By heating the solution, the organic solvent changes into a gas and mainly evaporates, leaving the solid residue behind.

Condensation

Condensation is the process by which water vapour transforms into liquid form when it comes into contact with a colder surface. Example: When boiling water, water droplets form on a metallic lid.

Churning

It is the process of removing a suspended solid’s lighter particles from a liquid. For instance, using milk or curd to make butter.

Also Read: NCERT Class 6 Science Chapter 2 Notes: Sorting Materials into Groups

Important Definitions in NCERT Class 6 Science Chapter 3

This section contains definitions of all important terms mentioned in CBSE Class 6 Science Chapter 3. Go through all the terms and definitions to learn about different concepts of substances and their components.

Pure Substances

Substances containing single constituent particles/compounds/elements are known as pure substances. Common examples include copper, iron, aluminium, etc.

Impure Substances

Any substance that is made up of more than one component is called an impure substance. Some common examples are water, milk, and salt. 

Impurities

These are unwanted components or particles in a substance. Common examples include stone in rice, sand in water, and dust particles in sugar. 

Mixtures

When more than one particle or compound is combined to form a substance, it is known as a mixture. One of the ordinary examples is the air. It contains gases like nitrogen, carbon dioxide, oxygen, noble gases, dust particles, water droplets, etc.

Homogeneous Mixtures

Mixtures in which constituent particles are invisible are termed homogeneous mixtures. Certain examples of homogeneous mixtures are soft drinks, air, and solution of water and sugar. 

Heterogeneous Mixtures

Mixtures in which constituents are easily visible are termed heterogeneous mixtures. Certain examples of heterogeneous mixtures are dust particles in air and oil in water.

Solution

A homogenous mixture is created when a soluble ingredient is completely dissolved in a liquid (for example, salt in water). It is referred to as a remedy.

Saturated Solution

A solution is said to be saturated when there is no longer any soluble material that can be dissolved at normal temperature.

Solubility

Solubility is the ability of a substance to dissolve in a liquid, like water. If something is soluble, it means it can mix and disappear in the liquid to make a solution. If it is not soluble, it will not dissolve and will stay separate.

Download NCERT Science Class 6 Science Chapter 3  Important Questions and Answers PDF

Explore all the Chapters of Class 6 Science:-

Chapter 1	Chapter 2	Chapter 4	Chapter 5	Chapter 6
Chapter 7	Chapter 8	Chapter 9	Chapter 10	Chapter 11

Important Questions in CBSE Class 6 Science Chapter 3

Here, we have compiled all important questions in the Exercises of NCERT CBSE Class 6 Science Chapter 3. We have tried to provide the best possible answers. Refer to the answers and make learning easy. 

Ques 1: What is the need for separating different components of a mixture? Also, provide two examples

Ans: Separation of substances is done to get a purified form of a product by removing the unwanted particles. Here are two examples of the separation of different components from a mixture:

• Removing husk from pulses
• Removing  sugar from water

Ques 2: What do you mean by winnowing? Where can it be used?

Ans: It is a separation technique used to separate heavier components from lighter ones in a mixture through the wind. It can be used to remove grains from the husk after the chaff has been removed from the grains.

Ques 3:  How will you remove dirt particles or husk from pulses?

Ans: Dirt particles or husk can be separated from pulses using wind. The wind will blow away the husk from pulses as the former is lighter than the latter. 

Ques 4: What do you mean by seiving? Where can it be used?

Ans: It is the technique of segregating smaller particles from large ones using a sieve. It is commonly used at building sites to remove pebbles and stones from sand. It can also be used in flour mills to purify wheat and refined flour.

Ques 5: How can you separate sand from water?

Ans: Sand is heavy and will settle to the bottom if left undisturbed, therefore sedimentation and decantation can be employed to remove it from water. Decantation makes it simple to separate the top layer of water.

Ques 6: Can you separate sugar and wheat from their mixture? If yes, how can you do it?

Ans: Yes, sieving can be used to separate sugar from wheat flour. Sugar will remain on a sieve due to the difference in particle sizes, while fine grains of wheat flour will pass through.

Ques 7: How can you get clear water from a small sample of muddy water?

Ans: By using the filtration procedure, we will be able to produce clear water from a sample of muddy water. Such a filter has very small pores, and it is covered with filter paper. A funnel contains a cone-shaped piece of filter paper that has been folded.

Ques 8: Which of the following statements are true or false?

1. A mixture of water and milk can be segregated through filtration.
2. Winnowing is used to separate powdered sugar and salt.
3. Sugar can be removed from tea through filtration
4. Decantation is used to segregate husk and grain

Ans: 

1. False
2. False
3. False
4. False

Ques 9: Fill in the blanks:

1. The technique of separating paddy seeds from their stalks is known as_______________.
2. Salt is separated from seawater through the process of_________________.
3. When muddy water was left in a bucket overnight, the impurities collected at the bottom. Then, from the top, the clean water was poured off. The separation method employed in this example is known as __________.
4. When milk is poured onto a piece of cloth after it has been boiled and cooled, the cream (malai) is left behind. This method of separating milk and cream is an illustration of __________.

Ans: 

1. Threshing
2. Evaporation
3. Sedimentation
4. Filtration 

Also Read: All You Need to Know About Science Stream Subjects

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